1. Field
Apparatuses and methods consistent with exemplary embodiments relate to signal transmission using an Orthogonal Frequency Division Multiplexing (OFDM) method.
2. Description of the Related Art
Recent communication services have had multi-functions and high qualities. In particular, the development of electronic technologies has increased distribution of portable broadcasting devices such as a high-definition digital television (TV), a high specification smartphone, etc. Therefore, demands for various reception methods and various service supports of broadcasting services have increased.
According to these demands, a broadcasting communication standard, such as Digital Video Broadcasting-the Second Generation Terrestrial (DVB-T2), has been developed as an example. The DVB-T2 is a second generation European terrestrial digital broadcasting standard that improves a performance of DVB-T that is adopted as a standard in 35 or more nations of the world including Europe. The DVB-T2 applies recent technologies, such as Low Density Parity Check (LDPC) codes, 256-Quadrature Amplitude Modulation (256QAM) methods, etc., to realize increases in a transmission amount and high bandwidth efficiency. Therefore, the DVB-T2 may provide various high-quality services such as high definition TV (HDTV) in a limited band.
According to the DVB-T2, the number of active carriers increases in proportion to increases in a Fast Fourier Transform (FFT) size, and sizes of a side lobe of a bandwidth edge varies with the FFT size. Here, the DVB-T2 determines the number of active carriers according to the smallest FFT size, and increases and uses the number of active carriers in proportion to the FFT sizes. If the number of active carriers is increased and used in proportion to the FFT size as described above, there is still a possibility to use more active carriers. Therefore, the existing DVB-T2 may be inefficient.
Therefore, there is a need for a criterion and a method for determining the number of usable active carriers.